JP2008207319A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad achieving high efficiency of polishing and high degree of flatness together. <P>SOLUTION: In this polishing pad having a polishing layer and used by sticking it onto a surface of a surface plate, a value of hardness of microrubber A of the polishing pad measured from a polishing surface side is smaller than a value of hardness of the polishing pad measured by an Asker C from the polishing surface side, by 12 or more, and the value of hardness measured by the Asker C is 60 or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing pad used for polishing a flat workpiece, and more particularly to a polishing pad used in a polishing process that requires high flatness such as polishing of a silicon wafer.

  High surface flatness is required in fields such as silicon wafers, magnetic hard disk substrates, magnetic head substrates, display glass substrates, photomask substrates, optical lenses, and optical waveguides for manufacturing semiconductor integrated circuits such as ICs and LSIs. Has been. In particular, elements and disks for information processing and information recording are required to dramatically increase the degree of integration, and along with this, the miniaturization of patterns such as circuits formed on a substrate has progressed, and therefore, High precision surface finish is strongly demanded.

  Polishing for smoothing and mirror-finishing a substrate such as a silicon wafer is performed by rotating and revolving the wafer placed against the surface plate while fixing the polishing pad to a rotatable surface plate and rotating it. In addition, the wafer surface is polished and flattened and smoothed by adding polishing slurry to the gap between the polishing pad and the wafer.

  In recent years, the size of silicon wafers has increased, and in order to increase the yield of chips from a single wafer, fringing of the outer periphery of the wafer has been suppressed as much as possible, the flatness of the workpiece has been improved, and the edge exclusive has been improved. It is required to reduce John (the width in the diametrical direction of the outer peripheral portion of the wafer that is not considered when evaluating the in-plane uniformity of the wafer after polishing). For example, a silicon wafer having a diameter of 200 mm or 300 mm is required to suppress edge exclusion to 2 mm or less.

  Various countermeasures have been proposed for the purpose of suppressing the wobbling of the outer periphery of the wafer.

  For example, a polishing method for reducing the difference in thickness between an object to be polished and a carrier is disclosed (Patent Document 1). A polishing method is disclosed in which a part of an object to be polished protrudes outward from the outermost edge portion of the effective processing surface of a surface plate or a polishing pad during polishing (Patent Document 2).

  Silicon wafer polishing pads include those obtained by impregnating a polyester non-woven fabric with a urethane resin and those obtained by foaming a single urethane resin. In order to obtain a highly flat wafer, a method using a harder polishing pad is employed. A method is disclosed in which a nonwoven fabric is first impregnated with thermoplastic polyurethane and then secondarily impregnated with a harder thermoplastic polyurethane (Patent Document 3). Further, as a countermeasure against the laminated structure, a polishing sheet made of a cloth sheet and a base sheet to which the cloth sheet is attached is disclosed (Patent Document 4). Furthermore, a polishing pad is disclosed in which a polishing sheet made of a woven fabric of synthetic fibers is laminated on an elastic sheet that is softer than the polishing sheet (Patent Document 5).

  However, although these polishing methods and polishing pads can improve the flatness to some extent, they are still insufficient, and there is a problem that the polishing efficiency is lowered and the surface roughness of the wafer is deteriorated. .

Japanese Patent No. 3400765 JP 2001-246554 A Japanese Patent Laid-Open No. 5-8178 JP 2002-86348 A JP-A-55-90263

  The present invention has been made in view of the problems in the conventional polishing method and polishing pad as described above, and provides a polishing pad that can achieve both a high level of polishing efficiency and flatness.

In order to solve the above problems, the polishing pad of the present invention has the following constitution (1).
(1) A polishing pad having a polishing layer that is used by being attached to the surface of a surface plate, the micro rubber A hardness value of the polishing pad measured from the polishing surface side, the polishing measured from the polishing surface side A polishing pad characterized by being 12 or more smaller than the Asker C hardness value of the pad and having an Asker C hardness value of 60 or more.

In the polishing pad of the present invention, more preferably, the polishing pad has a specific configuration of any one of the following (2) to (24).
(2) The polishing pad according to (1) above, wherein the micro rubber A hardness value is less than 90.
(3) The polishing pad according to (2) above, wherein the amount of compressive deformation of the polishing pad measured from the polishing surface side is less than 100 μm.
(4) The polishing pad according to any one of (1) to (3), wherein the polishing pad has a density of 0.8 g / cm ³ or more.
(5) The polishing pad according to any one of (1) to (4), wherein the polishing layer contains fibers.
(6) The polishing pad according to (5), wherein the fiber has a single fiber fineness of 3 dtex or less.
(7) The polishing pad according to (5) or (6), wherein the polishing layer is made of a fiber fabric.
(8) The polishing pad according to (7), wherein the fiber fabric is a woven fabric or a knitted fabric.
(9) The polishing pad according to any one of (1) to (8) above, wherein the thickness of the polishing layer is less than 1 mm.
(10) The polishing layer has a surface coated with ultrafine fibers, and the surface coverage of the ultrafine fibers is 70% or more, wherein any of the above (1) to (9) The polishing pad as described.
(11) The polishing pad according to (7) or (8) above, wherein the compressive energy of the fiber fabric is 0.05 gf · cm / cm ² or more.
(12) The polishing pad according to (7) or (8) above, wherein the compression recovery energy of the fiber fabric is 0.02 gf · cm / cm ² or more.
(13) A laminated polishing pad having a base layer laminated on the surface plate side of the polishing layer, wherein the micro rubber A hardness of the surface layer as the polishing layer is 3 or more smaller than the micro rubber A hardness of the base layer, The polishing pad according to any one of (1) to (12) above, wherein the underlayer has a micro rubber A hardness of 50 or more.
(14) The compression rate of the laminated polishing pad measured from the surface layer side is less than 5%, and the compression rate of the laminated polishing pad measured from the surface layer side is larger than the compression rate of the base layer. The polishing pad according to (13) above.
(15) The polishing pad as described in (13) or (14) above, wherein the foundation layer is made of a resin layer.
(16) The polishing pad according to any one of (1) to (15) above, wherein the polishing layer has a surface roughness Ra of 5 μm or more.
(17) The polishing pad as described in (15) above, wherein the resin layer is substantially non-water-absorbing.
(18) The polishing pad according to (17) above, wherein the density of the resin layer is 0.8 g / cm ³ or more.
(19) The polishing pad according to any one of the above (13) to (18), wherein the amount of compressive deformation of the underlayer is 20 μm or less.
(20) The polishing pad according to any one of (13) to (19) above, wherein the base layer has a bulk modulus of elasticity of 40 MPa or more and a tensile modulus of 0.1 MPa to 20 MPa. .
(21) The polishing pad according to any one of (13) to (20) above, wherein the value of tan δ at 100 Hz of the base layer is 0.03 or more and 0.25 or less at 25 ° C.
(22) The polishing pad as described in any one of (13) to (21) above, wherein a hysteresis loss rate when the underlayer is pressed by 25% is 10% or more and 32% or less.
(23) The polishing pad as described in any one of (1) to (22) above, which is used for polishing a silicon wafer.
(24) The polishing pad according to any one of (1) to (22) above, which is used for polishing a glass substrate.

  According to the present invention, a polishing pad having high polishing efficiency and excellent flatness can be obtained.

  The polishing pad of the present invention is a polishing pad in which the micro rubber A hardness of the polishing pad measured from the polishing surface side is 12 or more smaller than the Asker C hardness of the polishing pad measured from the polishing surface side, and the Asker C hardness is 60 or more. It is necessary to be.

  Here, the micro rubber A hardness of the polishing pad measured from the polishing surface side refers to the micro rubber A hardness measured by applying a micro rubber A hardness meter to the polishing surface of the polishing pad. Even when the polishing pad is very thin, for example, 0.1 mm, it refers to a value obtained by measuring a sample placed on a stainless steel plate having a thickness of 1 mm with a micro rubber A hardness meter. Further, the Asker C hardness of the polishing pad measured from the polishing surface side refers to the hardness measured by applying a pusher of an Asker C hardness meter to the polishing surface of the polishing pad. Even when the polishing pad is very thin, for example, 0.1 mm, it refers to a value obtained by measuring a sample placed on a stainless steel plate having a thickness of 1 mm with an Asker C hardness meter.

  Here, the micro rubber A hardness means a value measured in a state where the polishing pad is fixed with the back surface tape when the back surface tape is provided in the same manner as in actual polishing. Hereinafter, the micro rubber A hardness of the polishing pad refers to that measured from the polishing surface side, and the same applies to the Asker C hardness. The same applies to the compression rate and the amount of compressive deformation described later.

  In the present invention, the polishing pad preferably has a micro rubber A hardness of the polishing pad measured from the polishing surface side of 20 or more smaller than the Asker C hardness of the polishing pad measured from the polishing surface side. More preferably, the polishing pad has a micro rubber A hardness measured from the polishing surface side that is 30 or more smaller than the Asker C hardness of the polishing pad measured from the polishing surface side. In addition, when the difference between the two hardness values is smaller than 12, it is not preferable because the effect of reducing the wrinkle cannot be obtained.

  In the present invention, the micro rubber A hardness value is preferably less than 90, more preferably less than 80, and particularly preferably less than 70. This is because the smaller the value of the micro rubber A hardness is, the better the flatness is, the higher the polishing efficiency is, and the scratches are less likely to occur.

  On the other hand, the lower limit value of the micro rubber A hardness value is preferably around 50, more preferably around 55, and even more preferably around 60. This is because when the micro rubber A hardness is less than 50, minute waviness is formed on the polished surface of the workpiece, and the flatness is lowered.

  In the polishing pad of the present invention, the amount of compressive deformation of the polishing pad is preferably less than 100 μm, more preferably less than 80 μm, and particularly preferably less than 60 μm. That is, it is preferable that the amount of compressive deformation of the polishing pad measured by applying an indenter to the polishing surface is small, and the polishing pad is more difficult to be deformed by pressing. The amount of compressive deformation of the polishing pad is preferably 10 μm or more, and more preferably 20 μm or more. This is because polishing corresponding to a minute inclination of the polished surface is possible. A material in which the amount of compressive deformation of the polishing pad is 0 and does not deform at all with respect to the pressures P1 and P2 is not preferable as the polishing pad of the present invention (the pressures P1 and P2 will be described later). Incidentally, the measurement of the amount of compressive deformation of the polishing pad in the present invention is performed when the polishing pad itself used for polishing, that is, when the polishing pad is provided with a back surface tape just as in actual polishing, the back surface tape. The value measured with a polishing pad having a thickness used for polishing in a state of being fixed to the sample stage.

  In the polishing pad of the present invention, when polishing a workpiece such as a bare silicon wafer or an optical glass plate, the polishing layer moves the polishing layer and the workpiece relative to each other under a load through the slurry, thereby processing the workpiece. It is disposed on the polishing surface of the polishing pad in order to scrape off the surface layer of the object, flatten it, and smooth it.

  The polishing layer preferably contains fibers. In general, fibers are classified into natural fibers (cotton, hemp, wool, animal hair, silk, etc.) and chemical fibers, and chemical fibers are regenerated fibers (rayon, cupra, lyocell, etc.), semi-synthetic fibers (acetate, triacetate, etc.) ) And synthetic fibers. The fibers of the present invention are not particularly limited, but synthetic fibers are preferably used in that fibers having a constant cross-sectional shape from a small diameter to a large diameter can be obtained. Examples of the synthetic fiber include polyester, nylon, acrylic, vinylon, polypropylene, polyurethane, polyphenylene sulfide, and the like, and polyester and nylon are preferably used.

  Part or all of the fibers of the present invention preferably have a single fiber fineness of 3 dtex or less, more preferably 1 dtex or less, and particularly preferably 0.3 dtex or less. It is also preferable to use fibers having different single fiber fineness in combination. As described later, it is also preferable to use a combination of ultrafine fibers of 1 dtex or less and fibers exceeding 1 dtex. It is further preferable to use a combination of ultrafine fibers of 0.5 dtex or less and fibers exceeding 1 dtex. It is also particularly preferable to use a combination of ultrafine fibers of 0.1 dtex or less and fibers exceeding 1 dtex. When combining these ultrafine fibers and fibers exceeding 1 dtex, it is preferable to dispose the ultrafine fibers on the surface of the polishing layer. Here, 1 dtex refers to the number of grams per 10,000 m of fibers.

  The polishing layer of the present invention preferably contains the above fibers. In particular, an ultrafine fiber is preferable. The ultrafine fiber refers to a fiber having a single fiber fineness of 1 dtex or less. The ultrafine fiber preferably has a single fiber fineness in the range of 0.001 to 1 dtex, more preferably in the range of 0.01 to 0.5 dtex, and 0.01 to 0.1 dtex. It is particularly preferred. Use of ultrafine fibers is preferable because fine irregularities are formed on the surface of the polishing layer, slurry retention is improved, and polishing efficiency is improved. Moreover, it is preferable because the surface smoothness of the glass substrate or wafer to be polished is improved.

  The surface (polishing surface) of the polishing layer of the present invention is preferably such that ultrafine fibers cover 70% or more of the polishing layer surface, and more preferably 90% or more. Since the finer fiber diameter forms a more undulating polishing layer surface, it is preferable in terms of flatness, polishing processing efficiency, and surface smoothness of the object to be polished. It is preferable that the coverage is in the range of 70% to 100%.

  The fiber diameter of the fiber of the present invention is preferably 25 μm or less, more preferably 15 μm or less, particularly preferably 7 μm or less, and particularly preferably 3 μm or less. The lower limit of the fiber diameter of the fiber is around 0.05 μm.

The polishing layer of the present invention is particularly preferably a fabric made of the fibers. Examples of the fabric include woven fabric, non-woven fabric, felt, and the like. Particularly preferred as the woven fabric is a woven fabric or a knitted fabric.
The fabric of the present invention is preferably composed only of fibers. It is preferable that after the formation of the fabric, a resin component such as polyurethane or polyester is impregnated and the inter-fiber or fabric gap is covered with the resin component and not modified.

  The thickness of the polishing layer of the present invention is preferably less than 1 mm. Even if the polishing material is the same, the amount of compressive deformation increases as the thickness of the polishing layer increases, and when the workpiece is pressed against the pad, the pad deforms greatly and sinks deeper. It is. The lower limit of the thickness is around 0.1 mm.

  The polishing pad of the present invention includes at least a polishing layer and a back surface tape layer for fixing the polishing layer to a surface plate. Usually, the back tape layer plays a role of fixing the pad to the surface plate by peeling off the plastic film or release paper (referred to as a separator) before polishing and pressing the polishing pad against the surface plate. The back surface tape layer excluding the separator preferably has a thickness of 30 to 300 μm, more preferably 50 to 150 μm. The back tape layer is made of pressure-sensitive and hot-melt adhesive layers such as acrylic, butadiene, isoprene, olefin, styrene, and isocyanate. You may use the provided back surface tape layer. Usually, the substrate has a thickness of 20 to 200 μm.

  Further, the polishing pad of the present invention may be provided with a base layer on the surface plate side of the polishing layer. In the present invention, a laminated polishing pad refers to a laminate composed of at least two layers, a surface layer and a base layer, which are polishing layers.

  In the present invention, in the case of a laminated polishing pad, it is preferable that the micro rubber A hardness of the surface layer as the polishing layer is 3 or more smaller than the micro rubber A hardness of the underlayer. 5 or more is more preferable, 10 or more is particularly preferable, and 15 or more is particularly preferable. The upper limit of the difference value is preferably 40 according to the knowledge of the present inventors.

  In the present invention, in the case of a laminated polishing pad, the micro rubber A hardness of the surface layer as a polishing layer is preferably less than 90, more preferably less than 80, particularly preferably less than 70, and less than 65. It is much preferable that there is. The lower limit of the value is preferably 40 in terms of micro rubber A hardness according to the knowledge of the present inventors. Here, the micro rubber A hardness of the surface layer as the polishing layer refers to the micro rubber A hardness of only the polishing layer (surface layer). Even when the polishing layer is very thin, for example, 0.1 mm, it refers to a value obtained by measuring a sample placed on a stainless steel plate having a thickness of 1 mm with a micro rubber A hardness meter. Further, the micro rubber A hardness of the underlayer refers to the micro rubber A hardness measured in the state of only the under layer. The micro rubber A hardness of the polishing layer (surface layer) or the underlayer refers to a value obtained by measuring only the polishing layer (surface layer) or the underlayer. Therefore, the value measured in the state without the back surface tape or intermediate layer for fixing the polishing layer (surface layer) or the underlayer is said. The same applies to the compression rate and the amount of compressive deformation described later.

  In the present invention, the micro rubber A hardness of the laminated polishing pad measured from the surface layer side is preferably less than 90, more preferably less than 80, and particularly preferably less than 70. This is because the smaller the micro rubber A hardness of the laminated polishing pad measured from the surface layer side is, the better the flatness is, the higher the polishing efficiency is, and the scratches are less likely to occur. Meanwhile, the lower limit of the micro rubber A hardness of the laminated polishing pad measured from the surface layer side is preferably about 50, more preferably around 55, and particularly preferably around 60. When the micro rubber A hardness of the laminated polishing pad measured from the surface layer side is less than 50, minute waviness is formed on the polished surface of the workpiece, and a problem arises in terms of flatness.

  Here, the micro rubber A hardness of the laminated polishing pad measured from the surface layer side means polishing in a state where the laminated polishing pad composed of the polishing layer (surface layer) and the underlayer is fixed with the back surface tape in the same manner as in actual polishing. Sometimes measured from the polishing layer (surface layer) side located on the side facing the object to be polished. Hereinafter, the micro rubber A hardness of the laminated polishing pad refers to the value measured from the surface layer side. The same applies to the compression rate and the amount of compressive deformation described later.

  The underlayer of the present invention preferably has a thickness of 0.25 mm or more. The thickness of the underlayer is preferably 0.25 mm to 2.5 mm, more preferably 0.30 to 1.5 mm, and particularly preferably 0.5 to 1.2 mm. If the underlayer is too thin, the role of the cushion cannot be sufficiently achieved, which is not preferable. On the other hand, if the underlayer is too thick, it is not economically preferable.

  Usually, a double-sided tape based on a polyethylene terephthalate (PET) film is used to fix the polishing pad to the surface plate, but when a woven or knitted fabric is fixed to the surface plate with such a double-sided tape, Even if this is defined as a laminated polishing pad, a PET film usually has a thickness of 0.01 to 0.2 mm, which is not preferable. Moreover, the PET film itself cannot fully serve as a cushion, which is not preferable.

  The micro rubber A hardness of the underlayer of the present invention needs to be 50 or more. Further, it is preferably 60 or more, more preferably 70 or more, and particularly preferably 80 or more.

  In the present invention, the compression rate of the laminated polishing pad is preferably less than 5%, more preferably less than 4%, particularly preferably less than 3%, and particularly preferably less than 2%. . This is because the softness of the surface layer, which is the polishing layer, increases the polishing efficiency during polishing and suppresses the generation of scratches. In general, the compression rate is affected by the thickness of the sample. If the sample is thick, the value of the compression rate becomes small even for the same material. The measurement of the compressibility of the laminated polishing pad in the present invention refers to a value measured using the laminated polishing pad used for polishing. The lower limit of the compressibility of the laminated polishing pad is around 0.3%.

  The compression rate of the underlayer of the present invention is not particularly limited, but is preferably less than 3%. As described above, as a preferred embodiment, the compression rate of the laminated polishing pad measured from the surface layer side is less than 5%, and the compression rate of the laminated polishing pad measured from the surface layer is preferably larger than the compression rate of the underlying layer. It is.

  In the present invention, the underlayer is preferably made of a substantially non-water-absorbing resin layer. The water absorption rate of the underlayer is preferably 5% or less, more preferably 4% or less, particularly preferably 3% or less, and particularly preferably 2% or less. The resin layer preferably does not contain fibers. This is because when fibers are contained, voids called voids are formed at the interface between the resin and the fibers, resulting in water absorption.

  In the present invention, the surface roughness Ra of the polishing layer is preferably 5.0 μm or more, more preferably 7.0 μm or more, and particularly preferably 10.0 μm or more. When the surface roughness is less than 5.0 μm, the slurry retention is low and the polishing efficiency is low. The upper limit of the surface roughness Ra of the polishing layer is preferably around 150 μm.

  In the present invention, by configuring the polishing layer as a woven fabric or knitted fabric, a large surface roughness of 5.0 μm or more can be imparted to the laminated polishing pad, and a high processing efficiency can be obtained during polishing. Or the polishing layer which consists of a knitted fabric is preferable. On the other hand, the surface roughness of the polishing layer is preferably less than 100 μm, more preferably less than 60 μm, and particularly preferably less than 50 μm. When the surface roughness of the polishing layer of the polishing pad becomes too large, the flatness of the glass substrate or wafer to be polished is lowered or the surface smoothness is lowered. In addition, the polishing pad and the object to be polished are in close contact with each other during polishing, and the energy required for relative movement between the polishing pad and the object to be polished becomes excessive.

  In the present invention, the material of the base layer is not particularly limited, but in addition to synthetic resins and elastomers such as polyurethane, polyester, polyamide, polyolefin, acrylic resin, ABS resin, natural rubber, butadiene rubber, isoprene rubber, neoprene (registered) Trademark) rubber, nitrile rubber, styrene copolymer rubber, olefin copolymer rubber, silicon rubber and the like. Among these, polyurethane is preferable from the viewpoints of productivity, processability, durability, and the like. Either a foamed sheet or a non-foamed sheet of these polymers can be used, but a non-foamed sheet is preferred from the viewpoints of hardness, compressibility, non-water absorption, volume elastic modulus, tan δ, and hysteresis loss.

In the present invention, the density of the base layer made of resin is preferably 0.8 g / cm ³ or more. 0.85-1.5 g / cm ³ is more preferable, and 0.9-1.3 g / cm ³ is particularly preferable.

  The underlayer of the present invention preferably has an amount of compressive deformation described below of 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. This is because if the amount of compressive deformation of the underlayer is large, the amount of sag after polishing becomes large. In addition, the amount of compressive deformation (T2-T1) of the underlayer is required to be 2 μm or more. Further, the amount of compressive deformation (T2-T1) of the underlayer is preferably 3 μm or more, and more preferably 5 μm or more. This is because polishing corresponding to a minute inclination of the polished surface is possible. A material in which the amount of compressive deformation of the underlayer is 0 and does not deform at all with respect to the pressures P1 and P2 is not preferable as the underlayer of the present invention (the pressures P1 and P2 will be described later).

  Moreover, it is preferable that the volume elastic modulus of the underlayer is 40 MPa or more and the tensile elastic modulus is 0.1 MPa to 20 MPa. If the volume elastic modulus of the underlayer is less than 40 MPa or the tensile elastic modulus is less than 0.1 MPa, the wrinkle after polishing is large, and the flatness of the wafer is lowered. Further, if the tensile elastic modulus is 20 MPa or more, the wafer is scratched during polishing, which is not preferable.

  Further, the value of tan δ in the dynamic viscoelasticity of the underlayer of the present invention is preferably 0.03 or more and 0.25 or less at 25 ° C. and 100 Hz. Only in this case, the surface shape of the polished silicon wafer does not become concave, and a flat shape is obtained from the center to the edge of the wafer. When the value of tan δ at 25 ° C. and 100 Hz is smaller than 0.03 or larger than 0.25, the surface shape of the wafer tends to deteriorate.

  Moreover, it is preferable that the hysteresis loss rate at the time of 25% indentation of a base layer is 10% or more and 32% or less. The polishing pad is repeatedly subjected to high pressure during polishing and reaches the limit of durability. It is preferable that the compression deformation and the compression elastic recovery are appropriately balanced. When the hysteresis loss exceeds 32%, the life of the polishing pad is shortened. When the hysteresis loss is less than 10%, the polishing efficiency is not stable.

  In the polishing pad of the present invention, an intermediate layer for bonding and fixing the polishing layer and the base layer may be provided between the polishing layer and the base layer. The intermediate layer preferably has a thickness of 30 to 300 μm, and more preferably 50 to 150 μm. The intermediate layer consists of pressure-sensitive and hot-melt adhesive layers such as acrylic, butadiene, isoprene, olefin, styrene, and isocyanate. The provided intermediate layer may be used. Usually, the substrate has a thickness of 20 to 200 μm.

  The polishing pad of the present invention is used by being attached to the surface of a polishing surface plate of a polishing machine for polishing.

  When the polishing pad of the present invention polishes a workpiece such as a bare silicon wafer or an optical glass plate, the polishing efficiency is high and dripping (sagging at the edge of the workpiece) is remarkably suppressed. The reason why polishing is possible is not always clear, but by using a polishing pad with the above-mentioned characteristics, the pressure distribution in the polishing surface of the workpiece can be made more uniform, so the occurrence of stagnation It is presumed that both the flatness and the polishing processing efficiency could be achieved because the polishing layer surface can exhibit high slurry retention and the polishing processing efficiency can be maintained high.

  The workpiece is pressed against the pad during polishing, and the pad deforms and sinks. Considering the pressure distribution in the polished surface of the workpiece at this time, a larger pressure is applied to the edge portion than to the center portion of the workpiece. That is, at the edge periphery of the workpiece, the polishing pad is in a transition state where the deformed state changes from the deformed state to the deformed open state. It also takes. As a result, it is considered that the edge portion of the workpiece is intensively polished and removed at the initial stage of polishing, and a squeezing phenomenon occurs. As the polishing progresses and the amount of polishing of the work piece increases, the wrinkle increases. When the pressure distribution in the polishing surface of the work piece finally becomes constant, the wobbling amount becomes constant. Since the process of occurrence of dripping is considered as described above, it is possible to suppress dripping if the pressure concentration at the edge portion that occurs in the initial stage of polishing can be alleviated as much as possible to achieve a uniform pressure distribution.

  The polishing pad of the present invention is a polishing pad in which the micro rubber A hardness of the polishing pad measured from the polishing surface side is 12 or more smaller than the Asker C hardness of the polishing pad measured from the polishing surface side. The needle shape of the hardness meter that measures the micro rubber A hardness is a circular cylinder with a diameter of 0.16 mm and a height of 0.5 mm, and the micro rubber A hardness is determined from the pushing depth of the push needle. can get. On the other hand, the pusher shape of the hardness meter for measuring the Asker C hardness is a hemisphere having a radius of curvature of 2.54 mm, and the Asker C hardness can be obtained from the pushing depth of the pusher needle. Therefore, in the present invention, a polishing pad having a characteristic that it is hard in a wide region (C hardness) but soft in a narrow region (micro rubber A hardness) at a certain level or more achieves both flatness and polishing processing efficiency. It is based on the knowledge that it is excellent.

In such a polishing layer that is soft in a narrow region and hard in a wider region, it is considered that pressure concentration at the edge portion of the workpiece is alleviated and the pressure distribution is made uniform. However, if the hardness of the entire polishing pad is too soft, the pressure distribution cannot be made uniform.
The polishing pad of the present invention has been found to be able to be realized in a polishing pad having seemingly contradicting physical properties of soft polishing in a narrow region and hard polishing layer in a wider region as a result of pursuing the reduction of flickering. It is. In addition, since the polishing layer of the present invention is excellent in slurry retention, high polishing processing efficiency can be obtained. At this time, since the pad is hard in a wide area, it is also important that the uniformity of the polishing efficiency over the entire workpiece can be obtained. As described above, it is speculated that the polishing pad of the present invention can achieve both high polishing efficiency and excellent flatness.

  The micro rubber A hardness in the present invention refers to a value measured with a micro rubber hardness meter MD-1 manufactured by Kobunshi Keiki Co., Ltd. (location: Nishiiri, Shimochi-cho, Kyoto, Kyoto). The micro rubber hardness tester MD-1 makes it possible to measure the hardness of thin and small objects that were difficult to measure with a conventional hardness tester, and is about 1/5 of the spring type rubber hardness tester (durometer) A type. Since it is designed and manufactured as a reduced model, a measurement value consistent with the hardness of the spring type rubber hardness tester A type can be obtained. The micro rubber hardness tester MD-1 is a cylindrical shape having a diameter of 0.16 mm and uses a push needle having a height of 0.5 mm. A load is applied by a cantilever plate spring, and the spring load is 22 mN at 0 point and 332 mN at 100 point. The descending speed of the push needle is controlled by a stepping motor and is in the range of 10 to 30 mm / second. Since the thickness of a normal polishing pad is smaller than 5 mm, it cannot be measured with a spring type rubber hardness meter A type, and a value measured with a micro rubber hardness meter MD-1 is adopted.

  The Asker C hardness in the present invention refers to a value measured with an Asker rubber hardness meter C type manufactured by Kobunshi Keiki Co., Ltd. (location: Shimochi-cho, Shimocho, Kyogyo-ku, Kyoto) according to JIS K7312. However, even when the thickness of the sample does not reach 10 mm, the measurement is performed with the thickness of the polishing layer or the polishing pad itself not measured by overlapping the samples. The Asker rubber hardness tester C type uses a hemispherical pusher with a radius of 2.54 mm. The spring load is 539 mN at 0 point and 8379 mN at 100 point. At the time of measurement, the measurement was performed using a constant pressure loader manufactured by Kobunshi Keiki Co., Ltd.

The compression rate in the present invention is set to (T1) when a pressure of 300 g / cm ² is applied with a dial gauge for 60 seconds using an indenter with a diameter of 5 mm at the tip, and subsequently the pressure at 1800 g / cm ² is set. When the thickness when applied for 60 seconds is (T2), the compression rate can be calculated according to the following equation.
Compression rate (%) = ((T1-T2) / T1) × 100

The amount of compressive deformation of the present invention refers to the value of T2-T1 (μm) in the measurement of the compression rate described above. That is, it refers to the pushing amount when the indenter is pushed from a pressure of 300 g / cm ² to a pressure of 1800 g / cm ² .

  The surface coverage of the ultrafine fibers of the polishing layer of the present invention is preferably 70% or more, more preferably 90% or more. The range is within the range of 70% to 100% as described above.

  The surface coverage of the ultrafine fiber refers to the ratio of the area occupied by the ultrafine fiber portion by observing a surface photograph of the fabric with an SEM (scanning electron microscope). Three photographs having an area of 2 mm × 2 mm or more were taken at an arbitrary location on the surface of the fabric, and the surface coverage of the ultrafine fibers was calculated from the images.

The fabric of the present invention preferably has a compression energy of 0.05 gf · cm / cm ² or more, and the compression recovery energy of the fabric is preferably 0.02 gf · cm / cm ² or more. Further, more preferably the compression energy is 0.08gf · cm / cm ² or more, compression recovery energy of the fabric and more preferably 0.04gf · cm / cm ² or more.

Here, the compression energy and the compression recovery energy refer to the compression energy and the compression recovery energy of the fabric per 1 cm ² measured by an automated compression tester KESFB3 manufactured by Kato Tech Co., Ltd. An example of the relationship between pressure and thickness in a compression cycle (when compression is increased and when compression is decreased) used when calculating compression energy and compression recovery energy is shown in FIG.

First, increasing the compression pressure P applied to the fabric from 0 gf / cm ² up to 50 gf / cm ^2, followed by reducing the compressive force from 50 gf / cm ² to 0 gf / cm ^2, the measured change in thickness therebetween the fabric To do. Assuming that the thickness at the compression pressure P = 0.5 gf / cm ² when the compression pressure is increased is T ₀ and the thickness at the compression pressure P = 50 gf / cm ² is Tm, the compression energy WC is the compression pressure P when the compression force is increased. = P (T) is an integrated value from T = To to Tm, and corresponds to the area under the curve P = P (T) in the section from To to Tm. On the other hand, the compression recovery energy WC ′ is a value obtained by integrating the value of the compression pressure P = P ′ (T) when the compression force is reduced from T = To to Tm, and the curve P = P ′ (T ) Corresponds to the area below.

  Further, the ratio value WC '/ WC of the compression recovery energy and the compression energy is called compression resilience RC, and means a compression recovery rate in one compression cycle in which the compression force is increased and the compression force is decreased. A higher compression recovery rate is preferable, but a higher compression energy value and a higher compression recovery energy value are more preferable than a high compression recovery rate.

  The polishing pad of the present invention, that is, the micro rubber A hardness value of the polishing pad measured from the polishing surface side is 12 or more smaller than the Asker C hardness value of the polishing pad measured from the polishing surface side, and the Asker C hardness A method for producing a polishing pad having a value of 60 or more is not particularly limited, but as a typical example, the polishing layer can move laterally within the polishing surface, and polishing is performed by pressure during polishing. It can be manufactured by using a material having such a movable structure in which the layer moves laterally within the polishing surface and the degree of movement differs between a wide region (C hardness) and a narrow region (micro rubber A hardness). it can. As such a material, it is preferable that the polishing layer contains fibers, particularly a fabric. In addition, it is preferable that after the formation of the fabric, a resin component such as polyurethane or polyester is impregnated to cover the gaps between the fibers or the fabric with the resin component so as not to be modified.

  In the present invention, the production method of the laminated polishing pad in which the micro rubber A hardness of the surface layer is 3 or more smaller than the micro rubber A hardness of the under layer and the micro rubber A hardness of the under layer is 50 or more is not particularly limited. However, as a typical example, a method in which a polishing layer and an underlayer are prepared and bonded together via an adhesive layer to form a laminated polishing pad is most preferable in terms of productivity and equipment. However, for example, a method of directly bonding the polishing layer and the base layer without providing an adhesive layer may be used. In the present invention, “lamination” means a state in which adjacent layers among the polishing layer, the underlayer, and / or other layers are physically or chemically fixed. Examples of the method for reducing the hardness of the polishing layer as the surface layer include a method for changing to a more flexible material, a method for forming a porous body by foaming, and a method for increasing the thickness of the polishing layer. In particular, when a fiber-containing layer or a fabric is used as the polishing layer, the polishing layer can be softened by selecting a bulky fiber or a bulky fabric structure and increasing its thickness. On the other hand, as a method of increasing the hardness of the underlayer, in addition to selecting a harder material, the hardness of the underlayer can be increased by a method of introducing a crosslinked structure.

  In particular, a laminated polishing pad having a micro-rubber A hardness of less than 90 of the laminated polishing pad measured from the surface layer side is, for example, when the hardness of the underlayer is 90 and the hardness of the polishing layer is lower than 90 The hardness of the laminated polishing pad measured from the surface layer side by laminating these can be less than 90. Further, even if the hardness of the underlayer is 90 and the hardness of the polishing layer is the same, the hardness of the laminated polishing pad measured from the surface layer side is selected by laminating a thin polishing layer and laminating it. Can be less than 90.

  Furthermore, a laminated polishing pad having a compression rate measured from the surface layer side of less than 5% and a compression rate of the laminated polishing pad measured from the surface layer side being larger than the compression rate of the underlayer is, for example, that of the polishing layer (surface layer) Even if the compression rate is 5%, by selecting a hard layer having a relatively small compression rate as the underlayer, the compression rate measured from the surface layer side is less than 5%, and the laminated polishing pad measured from the surface layer side It is possible to produce a laminated polishing pad having a larger compression ratio than that of the underlying layer.

  In addition, a laminated polishing pad having a surface roughness Ra of 5 μm or more is produced by using a polishing layer having a diameter of the fiber itself and / or irregularities (surface roughness) formed by overlapping of the fibers. be able to. As another method, it can be produced by using a polishing layer utilizing surface roughness based on closed cells and / or open cells.

  Furthermore, a laminated polishing pad in which the resin layer is substantially non-water-absorbing can be produced by forming a resin molded body having no foaming or a relatively small foaming rate.

Furthermore, a laminated polishing pad having a resin layer density of 0.8 g / cm ³ or more can be produced by forming a resin molded body having no foaming or a relatively small foaming rate.

  Furthermore, a laminated polishing pad in which the amount of compressive deformation of the underlayer is 20 μm or less can be produced by forming a resin molded body having no foaming or a relatively small foaming rate.

  Furthermore, a laminated polishing pad in which the volume elastic modulus of the underlayer is 40 MPa or more and the tensile elastic modulus is 0.1 MPa to 20 MPa is produced by forming a resin molded body having no foam or a relatively low foam rate. be able to.

  When polishing a workpiece such as glass or a silicon wafer using the polishing pad of the present invention, it is particularly preferably employed when the polishing amount is 2 μm or more, and more preferably 5 μm or more. The thickness is preferably 8 μm or more. That is, in general, polishing is performed in two steps: a rough polishing step that increases the amount of polishing processing, and a final polishing step that suppresses haze and removes fine flaws. Of these, the polishing pad of the present invention is employed in the rough polishing step. It is preferable to do. The reason for this is that if it is used in a final polishing process with a small amount of polishing, rather than a rough polishing step with a large amount of polishing, the amount of polishing will be too small to improve the edge shape and improve the flatness at the edge. It is because the effect of this cannot be expressed.

  The polishing pad of the present invention can be used for polishing electronic materials such as silicon wafers, compound semiconductor wafers, insulator films and metal films, hard disk substrates, and magnetic heads provided on these wafers. Further, it can be used as a polishing pad for polishing a semiconductor wafer, which is an object to be polished, for the purpose of planarizing the semiconductor wafer by a chemical mechanical polishing (CMP) technique. In the CMP process, a polishing pad made of a polishing agent and a chemical solution is used to move the semiconductor wafer and the polishing pad relative to each other, thereby polishing the semiconductor wafer surface and polishing and polishing the semiconductor wafer surface. Is used. As the polishing slurry, inorganic particles such as silica, alumina, ceria and diamond, organic particles such as acrylic, or a mixture containing inorganic particles and organic particles or composite particles can be used.

  The polishing pad of the present invention can also be used for polishing optical members such as glass substrates for liquid crystal displays, optical lenses, photomask substrates, optical prisms, optical filters, and optical waveguides. Examples of the material of the optical member to be polished include glass, quartz, crystal, sapphire, transparent resin, lithium tantalate, and lithium niobate.

  As other applications, ferrite, alumina, silicon carbide, silicon nitride, ceramics, alloys, resins and the like can be used for polishing.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these do not limit this invention. The evaluation method was performed as follows.

  Measurement of micro rubber A hardness, Asker C hardness, compression rate, and amount of compressive deformation of the polishing pad was done by peeling the release paper or release film on the back of the sample punched out to a size of 30 mm × 30 mm from the polishing pad It measured in the state which affixed.

(1) Micro rubber A hardness This was measured with a micro rubber hardness meter MD-1 manufactured by Kobunshi Keiki Co., Ltd. Different locations were measured three times on a 30 mm × 30 mm sample, and the average value was taken as the hardness value. If the three measurements do not fall within the range of ± 1, prepare two 30mm x 30mm samples, measure 9 different points on each sheet, and calculate the average of 18 points of data in total The hardness value was used.

(2) Asker C hardness Asker C hardness is a value measured using an Asker rubber hardness tester C type, and was measured according to the method described in JIS K7312 Appendix 2 with a sample size of 30 mm × 30 mm. Is. However, when the thickness is less than 10 mm, the JIS K7312 appendix 2 describes that the measurement is performed by stacking the samples to be 10 mm or more. In this regard, in the present invention, as described above, a single polishing pad is placed on a 1 mm thick stainless steel plate as it is, and a 30 mm × 30 mm sample is measured three times at different points. The value of

(3) Compressibility Using an indenter with a diameter of 5 mm, a sample thickness T1 when a pressure of 300 g / cm ² was applied to a sample of about 30 × 30 mm for 60 seconds, followed by a pressure of 1800 g / cm ² was applied for 60 seconds. The sample thickness T2 was measured and calculated from the compression ratio (%) = ((T1-T2) / T1) × 100. For the measurement of T1 and T2, a laser displacement meter was used, and the position of the indenter was measured at a predetermined timing. Different portions of the 30 × 30 mm sample were measured three times, and the average value was taken as the compression rate value.

(4) Amount of compressive deformation Using an indenter with a diameter of 5 mm, a sample thickness T1 when a pressure of 300 g / cm ² was applied to a sample of about 30 × 30 mm for 60 seconds, followed by a pressure of 1800 g / cm ² was applied for 60 seconds. The sample thickness T2 was measured and calculated from the amount of compressive deformation T2-T1 (μm). A laser displacement meter was used to measure T1 and T2, and the position of the indenter was measured at a predetermined time. Different locations were measured three times on a 30 mm × 30 mm sample, and the average value was taken as the value of the amount of compressive deformation.

(5) Density The density was measured using a pycnometer (Harvard type) according to the method described in JIS K7112. Measurement was performed on one sample of 30 mm × 15 mm. Measurement was performed three times using three samples, and the average value was taken as the density value.

(6) Water absorption The sample was vacuum-dried at 70 ° C. for 12 hours, and allowed to stand in a desiccator for 1 hour, and then the weight was measured (dry weight). At 23 ° C., the sample was immersed in purified water for 24 hours, the purified water on the surface was wiped off, and the weight was measured (wet weight).
The value of (wet weight−dry weight) / dry weight × 100 was defined as the water absorption rate.
Measurement was performed on one sample of 30 mm × 15 mm. Measurement was performed three times using three samples, and the average value was defined as the water absorption value.

(7) Measurement of fabric characteristics The compression energy of the fabric and the compression recovery energy of the fabric were measured by an automated compression tester KESFB3 manufactured by Kato Tech Co., Ltd.

(8) Surface Roughness Using a three-dimensional fine shape measuring instrument ET4000A (manufactured by Kosaka Laboratory Ltd.), the surface roughness of the unpolished laminated polishing pad was measured. The measurement area was set to 1000 × 1000 μm, and leveling processing by the least square method was performed under measurement conditions of an X pitch of 1 μm, a Y pitch of 4 μm, and an X feed rate of 0.1 mm / second.

(9) Volume modulus Measured by the method described in JP-A-2005-345228. In an environment of 23 ° C., a sample and water are put into a measurement cell (internal volume of about 43 mL) provided with a volume change detection unit, pressure isotropically applied to the whole measurement cell, and the sample is changed from the volume change. The bulk modulus was calculated. The volume elastic modulus was calculated from the volume change when 0.10 MPa was applied as the isotropic pressure.

(10) tan δ
It measured with the wide dynamic viscoelasticity measuring apparatus "DVE-V4" by Rheology Co., Ltd. After applying a static stress (about 7 g / mm ² ) to a sample 3 mm wide x 1-2 mm thick x 28 mm long (distance between chucks of about 20 mm), a sinusoidal distortion with a displacement amplitude of 40 μm at a frequency of 100 Hz In addition, the stress response generated at that time was measured, and the storage elastic modulus, loss elastic modulus, and loss tangent tan δ were calculated from the dynamic stress waveform and the dynamic strain waveform. The measurement was performed in a nitrogen gas stream at a temperature increase rate of 2 ° C./min (constant temperature increase) at 0 ° C. to 80 ° C.

(11) Hysteresis loss rate Measured with Tensilon manufactured by Toyo Baldwin. Samples having a size of 50 mm × 50 mm are laminated so as to have a thickness of 5 to 7 mm, and the entire surface is pressed in a thickness direction at a speed of 10 mm / min to a displacement amount of 25%, and then pushed at a speed of 10 mm / min. The operation of gradually reducing and returning the displacement to 0% is performed five times in succession, and the difference between the pressure energy at the time of pushing in and the pressure energy at the time of returning in the fifth cycle is divided by the fifth pressure energy. The calculated value was calculated as hysteresis loss.

(12) Polishing evaluation A
A polishing pad is attached to a single-side polishing machine LP-15F (manufactured by Lapmaster SFT) having a surface plate of 420 mmφ, and ceria slurry (ceria abrasive concentration of 5% by weight) is poured onto the polishing pad at a rate of 25 mL / min. However, the optical glass plate BK-7 having a thickness of 74 mm × 74 mm × 1 mm was polished for 10 minutes at a platen rotation speed of 40 rpm and a polishing pressure of 10 kPa. In Comparative Example 2, a # 170 diamond dresser was pressed onto the polishing pad and conditioned at a rotational speed of 50 rpm before processing. In Example 1, Example 2, and Comparative Example 1, polishing was performed without performing conditioning before processing. After the polishing process was completed, rinsing was performed with ion exchange water, and then the polishing process efficiency and the edge shape of the optical glass plate were measured.

(13) Polishing evaluation B
A polishing pad is attached to a single-side polishing machine LP-15F (manufactured by Lapmaster SFT) having a surface plate of 420 mmφ, and a colloidal silica slurry GLANZOX-1302 (manufactured by Fujimi Incorporated) is polished at a rate of 25 mL / min. While flowing upward, a 5-inch single crystal silicon wafer was polished for 20 minutes at a platen rotation speed of 40 rpm and a polishing pressure of 13.4 kPa. After the polishing was completed, rinsing with ion exchange water was performed, and then the polishing processing efficiency and the edge shape of the wafer were measured. In Comparative Example 3, a # 170 diamond dresser was pressed on the polishing pad at a pressure of 0.7 kPa and a rotation speed of 50 rpm for 5 minutes to perform conditioning before processing, and then polishing was performed. In Examples 3-7 and Comparative Examples 4-5, it grind | polished without performing the conditioning before a process.

(14) Polishing efficiency The weight change before and after polishing was measured with an electronic balance. In the polishing evaluation A, the polishing efficiency (μm / min) was calculated by dividing by the density (2.51 g / cm ³ ) of the optical glass BK-7, the area of the glass plate, and the polishing time. In the polishing evaluation B, the polishing efficiency (μm / min) was calculated by dividing by the density of single crystal silicon (2.329 g / cm ³ ), the area of the wafer, and the polishing time. Before and after polishing, the sample was washed with ion-exchanged water using a PVA sponge (made of polyvinyl formal resin) and weighed after drying.

(15) Edge shape The edge shape of a glass plate (74 mm square) and a 5-inch single crystal silicon wafer was measured by a three-dimensional fine shape measuring instrument ET4000A (manufactured by Kosaka Laboratory Ltd.). Leveling processing was performed by the least square method. An approximate straight line in the range of 3 mm to 6 mm is obtained from the edge of the surface shape, and the amount of wobbling is traced from the center of the workpiece to the edge direction based on the straight line. The distance (distance from the edge) was determined by using the position (distance)) as the corner start point and the position (distance from the edge) where the amount of fringe exceeds 0.10 μm for the first time as the boundary limit point. For those where the fringe start point is found inside the edge 3 mm, change the approximate straight line range from 5 mm to 10 mm from the edge, and find the fringe start point and the fringe limit point in the same manner as above. It was.

(16) Polishing evaluation C
A polishing pad is attached to a single-side polishing machine LP-15F (manufactured by Lapmaster SFT) having a surface plate of 420 mmφ, and fumed silica slurry Semi-Sperse 25 (manufactured by Cabot Microelectronics) is diluted twice. While flowing over the polishing pad at a rate of 20 mL / min, a 5-inch silicon oxide film wafer (oxide film thickness 1 μm) was polished for 1 minute at a platen rotation speed of 45 rpm and a polishing pressure of 30 kPa. After completion of polishing, rinsing with ion-exchanged water was performed, and the polishing rate and in-plane uniformity of the polishing rate were measured. In Comparative Example 6, a # 170 diamond dresser was pressed on the polishing pad at a pressure of 10 kPa and a rotation speed of 50 rpm for 60 minutes to perform conditioning before processing, and then polishing was performed. In Example 8, polishing was performed without performing conditioning prior to polishing.

(17) Polishing rate of oxide film Using Lambda Ace VM-2000 (manufactured by Dainippon Screen Mfg. Co., Ltd.), measurement was performed at predetermined 31 measurement points inside the edge of 1 mm in the diameter direction of the wafer. The average value of 31 polishing rates at each measurement point calculated from the following equation was defined as the polishing rate.
Polishing rate = (thickness of oxide film before polishing−thickness of oxide film after polishing) / polishing time

(18) In-plane uniformity of polishing rate of oxide film The in-plane uniformity of the polishing rate of the wafer was calculated according to the following equation.
In-plane uniformity (%) = (maximum polishing rate−minimum polishing rate) / (maximum polishing rate + minimum polishing rate) × 100

Example 1
As the polishing layer, a satin woven fabric using warp polyester yarn (fiber diameter 3.1 dtex) and weft yarn using sea-island type polyester ultrafine fibers (fiber diameter 0.07 dtex) was used. The micro rubber A hardness of the fabric alone was 73, the fabric thickness was 0.24 mm, the compression energy of the fabric was 0.15 gf · cm / cm ² , and the compression recovery energy of the fabric was 0.07 gf · cm / cm ² . Double-sided tape with release film (double-sided tape with adhesive layer on both sides of polyethylene terephthalate film, about 110 μm thick) is pasted on the back side of the polishing layer, then punched into a circle with a diameter of 420 mm, and the release film is It peeled and stuck on the surface plate and the grinding | polishing evaluation A was performed. The results are shown in Table 1.
Further, the thickness of the polishing pad is 0.36 mm, the micro rubber A hardness measured from the polishing surface side is 71, the Asker C hardness of the polishing pad measured from the polishing surface side is 95, and the amount of compressive deformation measured from the polishing surface side is It was 35.5 μm. Moreover, the surface coverage of the ultrafine fiber of the polishing pad was 95%.

Comparative Example 1
As the polishing layer, a plain weave structure fabric using sea-island polyester super extra fine fibers (corresponding to a single fiber fineness of 0.11 dtex and approximately 0.1 denier) was used for both the warp and the weft. This fabric is a woven fabric in which 70 polyethylene terephthalate fibers having a single fiber fineness of 0.11 dtex are bundled, and nine of these bundles are used as warp and weft. The micro rubber A hardness of the fabric alone was 89, and the fabric thickness was 0.19 mm. Double-sided tape with release film (double-sided tape with adhesive layer on both sides of polyethylene terephthalate film, about 110 μm thick) is pasted on the back side of the polishing layer, then punched into a circle with a diameter of 420 mm, and the release film is It peeled and stuck on the surface plate and the grinding | polishing evaluation A was performed. The results are shown in Table 1.
Further, the thickness of the polishing pad is 0.31 mm, the micro rubber A hardness of the polishing pad measured from the polishing surface side is 86, the Asker C hardness is 96, the compression rate is 10.5%, the amount of compressive deformation is 15.0 μm, The surface roughness was 11.5 μm.

Example 2
As the polishing layer, the same fabric as that used in Comparative Example 1 was used, and a laminated pad was produced as follows. As the underlayer, an acrylonitrile butadiene rubber sheet having a thickness of 2.10 mm was used. The physical properties of only the underlayer were as follows: micro rubber A hardness 91, Asker C hardness 95, compression ratio 0.65%, tan δ 0.24, and hysteresis loss 28%. The polishing layer and the underlayer were bonded together through an adhesive layer having a thickness of about 70 μm. Next, a double-sided tape with a release film (double-sided tape with an adhesive layer on both sides of a polyethylene terephthalate film, with a thickness of about 110 μm) was bonded to the back side of the underlayer, then punched into a circle with a diameter of 420 mm and released. The mold film was peeled off and adhered to a polishing surface plate, and polishing evaluation A was performed. The results are shown in Table 1.
The laminated rubber pad measured from the polishing surface side had a micro rubber A hardness of 76, an Asker C hardness of 95, a compression rate of 1.04%, and a compression deformation of 25.4 μm.

Comparative Example 2
As the polishing pad, foamed polyurethane MHC15A (made by Nitta Haas) containing ceria particles was punched into a circle having a diameter of 420 mm, the release film was peeled off and the polishing pad was adhered to a surface plate, and polishing evaluation A was performed. The results are shown in Table 1.
This polishing pad had a thickness of 1.64 mm, a micro rubber A hardness measured from the polishing surface side of 91, an Asker C hardness of 94 measured from the polishing surface side, and a compression deformation of 16.0 μm.

  By comparing Example 1 with Comparative Example 2, the polishing pad of the present invention has a polishing efficiency of 26% compared to a polishing pad (ceria particle-containing foamed polyurethane) generally used in polishing optical glass. High and excellent in polishing efficiency. In addition, as for the sag after polishing, the point where the squeeze amount becomes 0.02 μm (distance from the edge) and the point where the squeeze amount becomes 0.10 μm (distance from the edge) are both compared with the comparative example. It can be seen that it is greatly improved.

  In particular, in Example 1, the amount of compressive deformation is 35.5 μm, whereas in Comparative Example 2, the amount of compressive deformation is 16.0 μm, so the amount of sinking of the optical glass plate into the pad during polishing is Example 1 is considered larger. However, since the fluff is much smaller in Example 1, in the polishing pad of the present invention in which the micro rubber A hardness of the polishing pad is smaller than the Asker C hardness, the edge portion of the workpiece at the time of polishing It is presumed that this is the result of the effect of the pressure concentration being relaxed and the pressure distribution becoming uniform.

  Further, comparing Example 2 with Example 1, it can be seen that the misalignment is further improved by using a laminated pad rather than a single-layer pad.

  Furthermore, by comparing Example 2 with Comparative Example 1, it can be seen that even if the fabric is the same, if the laminated pad is used to satisfy the requirements of the present invention, the sag is improved.

Example 3
As the polishing pad, the same polishing pad as that used in Example 1 was used, and polishing evaluation B was performed. The results are shown in Table 2.

Example 4
As the polishing layer, the same fabric as that used in Example 1 was used, and a laminated pad was prepared as follows. A thermoplastic polyurethane sheet having a thickness of 1.11 mm was used as the underlayer. The physical properties of only the underlayer were as follows: the micro rubber A hardness was 92, the Asker C hardness was 97, the compression rate was 0.59%, and the density was 1.20 g / cm ³ . The polishing layer and the underlayer were bonded together through an adhesive layer having a thickness of about 70 μm. Next, a double-sided tape with a release film (double-sided tape with an adhesive layer on both sides of a polyethylene terephthalate film, with a thickness of about 110 μm) was bonded to the back side of the underlayer, then punched into a circle with a diameter of 420 mm and released. The mold film was peeled off and adhered to a polishing surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
Further, the micro-rubber A hardness of the laminated polishing pad measured from the polishing surface side was 59, the Asker C hardness was 91, the compression rate was 2.85%, the amount of compressive deformation was 40.6 μm, and the surface roughness was 19.3 μm. It was.

Example 5
As the polishing layer, a split split multifilament yarn made of polyester and nylon (single yarn fiber is 3.0 dtex, and the cross-sectional shape of the single yarn fiber is an 8-leaf shape whose center is made of a nylon component, and surrounds it. A fabric having a circular knitting structure using a split-divided fiber in which a polyester component is arranged in a form, and the polyester component after the split-dividing is 0.3 dtex. The micro rubber A hardness of the fabric alone was 59, and the fabric thickness was 0.51 mm. As the underlayer, a thermosetting polyurethane sheet having a thickness of 1.01 mm was used. The physical properties of only the underlayer are as follows: micro rubber A hardness is 91, compression rate is 0.50%, density is 1.19 g / cm ³ , bulk modulus is 355 MPa, tensile modulus is 9.7 MPa, and the amount of compressive deformation is 4.8 μm, tan δ was 0.17, and the hysteresis loss was 19%. The polishing layer and the underlayer were bonded together through an adhesive layer having a thickness of about 70 μm. Next, a double-sided tape with a release film (double-sided tape with an adhesive layer on both sides of a polyethylene terephthalate film, with a thickness of about 110 μm) was bonded to the back side of the underlayer, then punched into a circle with a diameter of 420 mm and released. The mold film was peeled off and adhered to a polishing surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
Further, the micro-rubber A hardness of the laminated polishing pad measured from the polishing surface side was 54, the Asker C hardness was 88, the compression rate was 4.82%, the amount of compressive deformation was 80.1 μm, and the surface roughness was 18.5 μm. It was.

Example 6
As the polishing layer, the same fabric as that used in Example 1 was used, and a laminated pad was produced as follows. A thermoplastic polyurethane sheet having a thickness of 1.14 mm was used as the underlayer. The physical properties of the underlying layer are: micro rubber A hardness 62, Asker C hardness 91, compression ratio 1.45%, density 1.14 g / cm ³ , water absorption 0.83%, tensile modulus is The amount of compressive deformation was 16.4 μm, the tan δ was 0.12, and the hysteresis loss was 15%. The polishing layer and the underlayer were bonded together through an adhesive layer having a thickness of about 70 μm. Next, a double-sided tape with a release film (double-sided tape with an adhesive layer on both sides of a polyethylene terephthalate film, with a thickness of about 110 μm) was bonded to the back side of the underlayer, then punched into a circle with a diameter of 420 mm and released. The mold film was peeled off and adhered to a polishing surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
Moreover, the micro rubber A hardness of the laminated polishing pad measured from the polishing surface side was 69, the Asker C hardness was 88, the compression rate was 3.71%, and the amount of compressive deformation was 50.7 μm.

Example 7
As the polishing layer, a plain weave fabric using sea-island polyester ultrafine fibers (single fiber fineness 0.05 dtex) was used for both warp and weft. The micro rubber A hardness of the fabric alone was 88, and the fabric thickness was 0.15 mm. A thermoplastic polyurethane sheet having a thickness of 0.32 mm was used as the underlayer. The physical properties of only the underlayer were as follows: the micro rubber A hardness was 92, the Asker C hardness was 98, the compression rate was 1.53%, and the density was 1.20 g / cm ³ . The polishing layer and the underlayer were bonded together through an adhesive layer having a thickness of about 70 μm. Next, a double-sided tape with a release film (double-sided tape with an adhesive layer on both sides of a polyethylene terephthalate film, with a thickness of about 110 μm) was bonded to the back side of the underlayer, then punched into a circle with a diameter of 420 mm and released. The mold film was peeled off and adhered to a polishing surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
Further, the micro rubber A hardness of the laminated polishing pad measured from the polishing surface side was 75, the Asker C hardness was 96, the compression rate was 2.33%, and the amount of compressive deformation was 13.2 μm.

Comparative Example 3
Suba 800 (manufactured by Nitta Haas) impregnated with a polyurethane resin in a nonwoven fabric was punched out into a circle having a diameter of 420 mm, the release film was peeled off, the polishing pad was adhered to a surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
This polishing pad had a thickness of 1.27 mm, a micro rubber A hardness measured from the polishing surface side of 82, an Asker C hardness of 92 measured from the polishing surface side, and a compression deformation amount of 30.3 μm.

Comparative Example 4
As the polishing pad, a commercially available polishing pad (Nippon Engis Polishing Cloth 410) was used. It was punched into a circle with a diameter of 420 mm, the release film was peeled off and adhered to a polishing surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
In this polishing pad, the surface layer was composed of a fabric layer composed of fibers having a single fiber fineness of about 7 dtex, and the base layer was composed of a resin sheet. The micro rubber A hardness of the fabric alone was 96. The physical property values of the underlayer alone were 0.50 mm in thickness, 97 micro rubber A hardness, and 99 Asker C hardness. Also, the micro rubber A hardness of the laminated polishing pad measured from the polishing surface side was 91, the Asker C hardness was 98, the compression rate was 0.91%, the amount of compressive deformation was 7.5 μm, and the thickness was 0.83 mm. .

Comparative Example 5
As the polishing layer, a plain weave structure fabric using nylon 66 fibers (fiber diameter: about 30 μm) was used for both the warp and weft. The micro rubber A hardness of the fabric alone was 83, and the fabric thickness was 0.32 mm. A thermoplastic polyurethane sheet having a thickness of 0.32 mm was used as the underlayer. The physical properties of only the underlayer were as follows: the micro rubber A hardness was 65, the Asker C hardness was 94, the compression rate was 1.46%, and the density was 1.14 g / cm ³ . The polishing layer and the underlayer were bonded together through an adhesive layer having a thickness of about 70 μm. Next, a double-sided tape with a release film (double-sided tape with an adhesive layer on both sides of a polyethylene terephthalate film, with a thickness of about 110 μm) was bonded to the back side of the underlayer, then punched into a circle with a diameter of 420 mm and released. The mold film was peeled off and adhered to a polishing surface plate, and polishing evaluation B was performed. The results are shown in Table 2.
Also, the micro-rubber A hardness of the laminated polishing pad measured from the polishing surface side was 82, the Asker C hardness was 92, the compression rate was 2.57%, the amount of compressive deformation was 19.0 μm, and the surface roughness was 8.8 μm. It was.

  From the above, by comparing Example 3 with Comparative Example 3, the polishing process efficiency is about 11% higher than that of a polishing cloth (polyurethane resin impregnated non-woven fabric) generally used for polishing silicon wafers. It was excellent in terms of processing efficiency. In addition, as for the sag after polishing, the point where the squeeze amount becomes 0.02 μm (distance from the edge) and the point where the squeeze amount becomes 0.10 μm (distance from the edge) are both compared with the comparative example. It can be seen that it is greatly improved.

  In addition, comparing Examples 4 to 7 with Example 3, it can be seen that in the laminated pad rather than the single-layer pad, the starting point and the limit point are the edge side, and the screening is further improved. .

  Furthermore, comparing Examples 4 and 5 with Examples 6 and 7, it can be seen that the greater the difference between the C hardness and the micro rubber A hardness in the laminated pad, the more the wrinkle is improved.

Example 8
Polishing evaluation C was performed using the same laminated polishing pad as in Example 5. The polishing rate was 3100 angstroms / minute, and the in-plane uniformity was good at 1.5%.

Comparative Example 6
IC-1000 (made by Rohm & Haas), a hard polyurethane resin having a foam structure, is punched into a circle with a diameter of 420 mm, the release film is peeled off, and the polishing pad is attached to a surface plate. went. The polishing rate was 2300 angstroms / minute, and the in-plane uniformity was 10.2%. This polishing pad had a thickness of 1.38 mm, a micro rubber A hardness 99 measured from the polishing surface side, an Asker C hardness 99 measured from the polishing surface side, and a compressive deformation amount of 6 μm.

  Compared with Comparative Example 6, in Example 8, the polishing rate was uniform up to the edge of 1 mm of the wafer, and the in-plane uniformity of the polishing rate was excellent.

FIG. 1 is a diagram showing an example of a relationship between applied pressure and fabric thickness in a compression cycle in a compression test.

Explanation of symbols

1 Relationship between compression pressure and thickness when compression force increases P = P (T)
2 Relation between compression pressure and thickness when compression force decreases P = P '(T)

Claims (24)

  A polishing pad having a polishing layer that is used by being attached to the surface of a surface plate, the micro rubber A hardness value of the polishing pad measured from the polishing surface side, and the Asker of the polishing pad measured from the polishing surface side A polishing pad, which is 12 or more smaller than the C hardness value and has an Asker C hardness value of 60 or more.   The polishing pad according to claim 1, wherein the micro rubber A hardness value is less than 90.   The polishing pad according to claim 2, wherein the amount of compressive deformation of the polishing pad measured from the polishing surface side is less than 100 μm. The polishing pad according to claim 1, wherein a density of the polishing pad is 0.8 g / cm ³ or more.   The polishing pad according to claim 1, wherein the polishing layer contains fibers.   The polishing pad according to claim 5, wherein the fiber has a single fiber fineness of 3 dtex or less.   The polishing pad according to claim 5 or 6, wherein the polishing layer is made of a fiber fabric.   The polishing pad according to claim 7, wherein the fiber fabric is a woven fabric or a knitted fabric.   The polishing pad according to claim 1, wherein the polishing layer has a thickness of less than 1 mm.   The polishing pad according to any one of claims 1 to 9, wherein the polishing layer has a surface covered with ultrafine fibers, and the surface coverage of the ultrafine fibers is 70% or more. The polishing pad according to claim 7 or 8, wherein the compression energy of the fiber fabric is 0.05 gf · cm / cm ² or more. The polishing pad according to claim 7 or 8, wherein the compression recovery energy of the fiber fabric is 0.02 gf · cm / cm ² or more.   A laminated polishing pad having a base layer laminated on the surface plate side of the polishing layer, wherein the micro rubber A hardness of the surface layer as the polishing layer is 3 or more smaller than the micro rubber A hardness of the base layer, and the base layer The polishing pad according to claim 1, wherein the micro rubber A has a hardness of 50 or more.   14. The compression rate of the laminated polishing pad measured from the surface layer side is less than 5%, and the compression rate of the laminated polishing pad measured from the surface layer side is larger than the compression rate of the foundation layer. The polishing pad described in 1.   The polishing pad according to claim 13 or 14, wherein the foundation layer is made of a resin layer.   The polishing pad according to claim 1, wherein the polishing layer has a surface roughness Ra of 5 μm or more.   The polishing pad according to claim 15, wherein the resin layer is substantially non-water-absorbing. The polishing pad according to claim 17, wherein the density of the resin layer is 0.8 g / cm ³ or more.   The polishing pad according to claim 13, wherein an amount of compressive deformation of the underlayer is 20 μm or less.   20. The polishing pad according to claim 13, wherein the under layer has a volume elastic modulus of 40 MPa or more and a tensile elastic modulus of 0.1 MPa to 20 MPa.   21. The polishing pad according to claim 13, wherein a value of tan δ at 100 Hz of the underlayer is 0.03 or more and 0.25 or less at 25 ° C. 21.   The polishing pad according to any one of claims 13 to 21, wherein a hysteresis loss rate when the underlayer is pushed by 25% is 10% or more and 32% or less.   The polishing pad according to any one of claims 1 to 22, wherein the polishing pad is used for polishing a silicon wafer.   The polishing pad according to any one of claims 1 to 22, wherein the polishing pad is used for polishing a glass substrate.

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